Coated metal and method of cold working the same



FIFSiUl Patented Aug. 17, 1954 UNITED STAT S lC-E "COATED METAL AND METHOD orroonn WORKING THE 'SAAWE Harley A. Montgomery, Highland Park, Edmurfd "Sulikowski, Hamtramck, and Wesley jJ. -Wo'jtowicz, Detroit, Mich, assignors to H. A. =Montgomery Company, a'corporationof Michi g an No Drawing. Application] anuary l, 1950, Serial No. 141,596

"8 Claims. "1

This invention relates-to coating compositions and methods for cold working metals, such as deep drawing-shearing, form rolling and the like.

An object of the invention is to provide improved methods 'for cold working metals in which surfaces of metal workpieces can be finished to a suitable lustre while workpieces still are fiat, and the workpieces can be coated and coiled or stacked without sticking together and subsequently can be cold worked without their surfaces marring.

Aiurther object of the invention is to provide improved coating compositions which effectively protect metal surfaces=against marring, which have good. adhesion 'to metal surfaces and yet exhibit no tackiness or blocking effect, and which are non-hygroscopic, non-corrosive, and readily soluble in mild alkaline solutions.

A further "object of the invention is to "provide improved "methods for cold working metals in which metalworkpieces are coated Withan aqueous emulsion'of resins,'proteins anda plasticizerprior to working, 'the co'atingprotecting "the surfaces of both' the'workpiece "andthe working dies against marring.

.Aiurther object of the'invention is to provide improved coating compositions which consist of-an aqueous emulsion of resins, "proteins and a plasticizer.

The resins which we use in these compositions-are water dispersions of disproportionated rosin. The latter is the product which results from treating rosin catalytically in such fashion as to effect simultaneous dehydrogenation and hydrogenation. The product is a mixture of resins difierent from natural rosin, such resins being chiefly dehydro, dihydro, "and tetrahydro abietic acid. The dispersing agentis a volatile alkali soap of resin acids which are present naturally in the rosin. The volatile alkali commonly is ammonia, although equivalents, such as morpholine or low boiling organic amines, are possible. The dispersions contain 40 to 50 percent solids. -Such dispersions are available commercially-from Hercules Powder Company, under the trade name Dresin'ol, of which 'at least those *Dresinols the manufacturer identifies by the numbers 236, 215, 238, 40, 205, 42 and 210B are suitable. Some-other Dresinols have sodium soaps as their dispersing agent and are not suitable for our-purposes.

'To facilitatedescribing and claiming the preseii't invention, we 'definethe-term resin dispersion as used "herein to mean "a water dispersion of "disproportionate'd resin in which the dispers- :2 ing agent is a *volatilealkali "soap of resin acids. Whendried, these "re's n 'disp'ersions form a rosin derivativaan d wenfi'ne the term rosinderivative as used 5 herein *to l mean 5 the dried "product of our resin dispersions.

v The protein's which "u's'e'inthe'se composie tio'nscan be Zein,'*soyabean glue, gelatin, alcumin or casein or -coinbinations thereof. At present we -"pre'fer"zeinprincipally because it is readily available in "high grade ror'm. In our compositions both the plas'ticizer and the "resin dispersion act as dispersing agents for proteins such as zein which do not disperse readily in water.

The plasticizers which we use in these compositions can be any one or any combination of the following:

CzHaOH Ethanolform'amid'e N-C2H4OH C2115 Dietliylaminoethanol CH: ens-daemon l nk "'2 wind 2 'm''thvl i propa'noi onion 'NH'r-O-CHzOH CHZOH Trishydroxymethylaininomethane It is seen that eachof these plasticizers containsthe grouping tr'alizes excess resin-acidsinthe resin dispersion.

SEARC SQ.

Corrosion inhibitors are desirable when the plasticizer is ethanolformamide, 2 amino 2 methyl 1 propanol or trishydroxymethylaminomethane, but ordinarily are not needed when the plasticizer is or contains diethylaminoethanol. The number of suitable corrosion inhibitors is very large, including for example, tributyl amine, thiourea, butyrophenone, amyl mercaptan, fatty acids, and alkali soaps, such as ammonium soap of coconut fatty acids. Anti-foam agents are desirable when the coating composition is applied to the metal by methods which agitate the composition, such as dipping the metal in a basket or tank, but they are not needed when the composition is applied by spraying or spreading with a knife or roller. $uitable anti-foam agents are polymerized silicones, such as Dow Chemical Companys Antifoam A, or octyl alcohol. A dye facilitates determining whether a coating is uniform and of the proper thickness. Almost any acid or basic water soluble dye can be used for this purpose.

We are aware of previous protective and decorative coating compositions which contain Zein, resin dispersions, and a plasticizer, commonly oleic acid. Nevertheless we believe such compositions containing our particular plasticizers and having our proportions are novel and that our method of cold working metals using these compositions as coatings is novel.

The composition contains the foregoing ingredients in about the following proportion by weight:

Per cent Protein 4 to-13 Resin dispersion (40 to 50 percent solids) 30 to 14 Plasticizer 1 to 4 Aqua ammonia (28 percent NH3) 0.5 to 1.5 Water Remainder In addition the composition can include:

Per cent Corrosion inhibitor to 2 Anti-foam agent; 0 to 0.01 Dye 0 to 0.01

Inasmuch as the resin dispersion contains 60 to 50 percent water and the aqua ammonia about 72 percent water, the total water content of the composition is about 78 to 90 percent, and the solids content about 22 to percent. When the solids content is 22 percent, the composition has syrupy viscosity and, when the solids content is about 20 per cent or less, the composition has a watery viscosity. Therefore control of the water and solids content within these narrow limits furnishes a most convenient way of controlling the viscosity. 7

The basic composition of the film after it has been deposited on a workpiece and the workpiece dried is as follows by weight:

Per cent Protein 20 to 65 Rosin derivative 60 to 30 Plasticizer 20 to 5 In formulating such compositions, first the protein is dispersed in all the added water at a temperature of 50 to 80 F. Next the resin dispersion is added to protein dispersion and the mixture stirred for aboot 15 minutes or until the mixture becomes a heavy cream. Then the aqua ammonia is added and then the other ingredients. The temperature should never exceed 100 F. at any stage.

Following are specific examples of composi- 4 tions which we have found produce satisfactory coatings according to the present invention. In each instance the percentages are by weight.

Example 1 Per cent Zein 10.5 Resin dispersion (45% solids) 22.3 Aqua ammonia (28% NHs) 1.1 Ethanolformamide 1.8 Water Remainder This composition is most suitable for coating heavy gauge metal which is to receive a severe ironing of its surface during its working.

Example 2 Per cent Zein 5.1 Resin dispersion (45% solids) 25.0 Aqua ammonia (28% NHS) 1.5 Ethanolformamide 1.0 Water Remainder This composition is most suitable for low tensile strength metals, such as aluminum and magnesium.

This composition has a high protein content which enhances its thermal stability.

Example 4 Per cent Zein 10.5 Resin dispersion (45% solids) 21.0 Aqua ammonia (28% NHs) 1.1 Diethylaminoethanol 1.1 Ethanolformamide 1.1 Water Remainder Example 5 Per cent Zein 8.7 Resin dispersion (45% solids) 17.4 Aqua ammonia (28% NH::) 0.9 Diethylaminoethanol 2.6 Water Remainder Erample 6 Per cent Zein 11.4 Resin dispersion (45% solids) 22.8 Aqua ammonia (28% NHs) 1.1 2 amino 2 methyl 1 propanol 2.2 Water Remainder Example 7 i Per cent Soya bean glue 10.5 Resin dispersion (45% solids) 20.0 Aqua ammonia (28% NH3) 1.0 Trishydroxymethylaminomethane 1.8 Water Remainder Example 8 Per cent Gelatin 10.5 Resin dispersion (45% solids) 20.0 Aqua ammonia (28% N113) 1.0 Trishydroxylmethylaminomethane 2.5 Water Remainder acseyzeer With all the foregoing compositions, it is seen the same ultimate composition canbe obtained with resin dispersions of different solids contents by adjusting the amount of wateradded.

Coating compositions of the present invention are applied to the surface of a metal workpiece after that surface firsthas been cleaned thoroughly. The workpiece can be of various metals, such as plain carbon steel, stainless or other alloy steel, aluminum, magnesium, brass and numerous others. If desired;, the surface can be polished to a high lustre while the workpiece still is flat before the coating is applied. Any usual procedure can be employed for applying the coating. For example, we have applied coatings successfully by dipping, spraying, spreading the composition with a roller or knife, and by flowing the composition over the metal. For coating by spraying or spreading with a knife, we find a low viscosity is best; for spreading the coating with a roller, we prefer a higher viscosity.

The coating thickness varies from 0.00003 and 0.001 inch. These limits are critical since thinner coatings do not protect the workpiece and. the working dies do not have sufficient clearance for thicker coatings. The optimum coating thickness depends on the gauge of the workpiece and on the severity of the working operation, with heavier coatings being used for more difficult operations. We have found 0.0001 inch is a good average coating thickness. The coating thickness can be controlled by the method of applying the composition and by varying the viscosity of the coating composition; the greater the viscosity, the thicker the coating. The coatings are stable and exhibit no tackiness or blocking effect when dried. Therefore they can be applied to the metal considerably in advance of working, for example, as the metal is bein finished in a strip mill.

The coating is dried and the coated workpiece then can be cold worked by any usual procedure, such as deep drawing, shearing, form rolling and the like. The coating effectively protects the surface against marring, so that if this surface has been polished it retains its lustre after working and is free of scratches or mars. For shearing metal workpieces, which we define as including blanking, piercing, cutting, and perforating, the coatings have special value in that they effectively protect the dies. The coatings are not hygroscopic, but they are easily removed from a workpiece after the latter has been deformed by washing with a mild alkaline solution.

From the foregoing description it is seen that the present invention furnishes coating compositions which effectively protect metal surfaces during cold working and at the same time do not 7 have the undesirable properties ot being corro .sive; hygroscopic, or exhibiting: a blocking effect.

According to the cold working method of the present. invention, the coating can be applied well in advance of deformation and the workpiece first can. be polished: to a high: lustrea The ab;-' sence of a blocking effect makesritipo'ssiblesto coil or stack metal workpieces Whose surfaces have been. coated.

While we. have described. only certain pre ferred embodiments of the. present invention, it

is apparent. other alternatives may arise- There-- I fore we do not wish to= be limited by our dis.- closure, but only by the scope of the appended claims.

We claim:

' 1.. A method. of cold working. a. metal work,- piece comprising cleaning and finishing the surface of' a workpiece, applying, to the surface a single coating which has a thickness of 0.00003 to 0.001 inch and is of a composition consisting by weight of the following:.

Per cent Protein 4to 13 Water dispersion of disproportionatcd' rosin ('40 to 50% solids) 30 to 14 Plasticizer lto 4 Aqua ammonia (28% NHa) 0.5 to 1.5

and Water 60 tQ-TO' the protein'being of the group consisting of. zeint. soya bean glue, gelatin, albumin, and casein and combinations thereof and the plasticizer being of the group consisting of ethanolformamide, diethylaminoethanol, 2 amino 2 methyl 1 propanol, and trishydroxymethylaminomethane and combinations thereof, drying the coating, cold woring the coated workpiece with the coating protecting its surface against marring, and removing the coating by washing with a mild alkaline solution.

'2. A method as defined in claim 1 in which the protein is zein and the plasticizer is ethanolformamide.

3. A method as defined in claim 1 in which the protein is zein and the plasticizer is diethylaminoethanol.

4. A method as defined in claim 1 in which the protein is zein and the plasticizer is 2 amino 2 methyl 1 propanol.

5. A method as defined in claim 1 in which the protein is zein and the plasticizer is trishydroxymethylaminomethane.

6. A method of perforating a metal workpiece comprising cleaning and finishing the surface of a workpiece, applying to the surface a single coating which has a thickness of 0.00003 to 0.001 inch and is of a composition consisting by weight of the following:

Per cent Protein 4to 13 Water dispersion of disproportionated rosin (40 to 50% solids) 30 to 14 Plasticizer lto 4 Aqua ammonia (28% NI-I3) 0.5 to 1.5

and Water 60 to '70 the protein being of the group consisting of zein, soya bean glue, gelatin, albumin, and casein and combinations thereof and the plasticizer being of the group consisting of ethanolformamide, diethylaminoethanol, 2 amino 2 methyl 1 propanol, and trishydroxymethylaminomethane and combinations thereof, drying the coating, per- 72 forating the coated workpiece with the coating protecting its surfaces and those of the perforating dies against marring, and removing the coating by washing in a mild alkaline solution.

7. A metal workpiece prepared for cold working having a single dry surface coating consisting by weight of the following:

Per cent Protein 20 to 65 Rosin derivative 60 to 30 Plasticizer 20 to 5 the protein being of the group consisting of zein,

soya bean glue, gelatin, albumin, and casein and combinations thereof and the plasticizer being of the group consisting of ethanolformamide, diethylaminoethanol, 2 amino 2 methyl 1 propanol, and trishydroxymethylaminomethane and combinations thereof, said coating permitting the worpiece to be cold worked without marring its surface.

8. A method of preparing a metal workpiece for cold Working comprising cleaning and finishing the surface of a workpiece, applying to the surface a single coating which has a thickness of 0.00003 to 0.001 inch and is of a composition consisting by weight of the following:

Per cent Protein 4 to 13 Water dispersion of disproportionated rosin (40 to 50% solids) 30 to 14 Plasticizer 1 to 4 Per cent Aqua ammonia (28% NHa) 0.5 to 1.5

and Water Remainder the protein being of the group consisting of zein, soya-bean glue, gelatin, albumin, and caseinand. combinations thereof, and the plasticizer being of the group consisting of ethanolformamide, diethylaminoethanol, 2 amino 2 methyl 1 propanol, and trishydroxymethylaminomethane and. combinations thereof, and drying the coating.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A METHOD OF COLD WORKING A METAL WORKPIECE COMPRISING CLEANING AND FINISHING THE SURFACE OF A WORKPIECE, APPLYING TO THE SURFACE A SINGLE COATING WHICH HAS A THICKNESS OF 0.00003 TO 0.001 INCH AND IS OF A COMPOSITION CONSISTING BY WEIGHT OF THE FOLLOWING: WATER DISPERSION OF DISPROPORTIONATED AND THE PROTEIN BEING OF THE GROUP CONSISTING OF ZEIN, SOYA BEAN GLUE, GELATIN, ALBUMIN, AND CASEIN AND COMBINATIONS THEREOF AND THE PLASTICIZER BEING OF THE GROUP CONSISTING OF ETHANOLFORMAMIDE, DIETHYLAMINOETHANOL, 2 AMINO 2 METHYL 1 PROPANOL, AND TRISHYDROXYMETHYLAMINOMETHANE AND COMBINATIONS THEREOF, DRYING THE COATING, COLD WORKING THE COATED WORKPIECE WITH THE COATING PROTECTING ITS SURFACE AGAINST MARRING, AND REMOVING THE COATING BY WASHING WITH A MILD ALKALINE SOLUTION. 